Polarisation control in VCSELs by elliptic surface etching

850 nm-wavelength vertical-cavity surface-emitting lasers (VCSELs) with an elliptical shallow surface relief having various aspect ratios and orientations have been fabricated. Using appropriate etch dimensions, VCSELs of up to 12.5 /spl mu/m active diameter are forced to operate on the fundamental mode for a certain current range. By aligning the longer axis of the etched ellipse with the [011] or [011~] crystal axis, the polarisation of the fundamental mode is pinned accordingly with a polarisation suppression ratio of /spl sim/30 dB.